Some electrical apparatus, e.g. a power supply apparatus, uses power semiconductor devices as its components. Power semiconductor devices are connected to a driver printed circuit board on which a driver circuit for driving the power semiconductor devices is formed. The driver printed circuit board is connected to a control printed circuit board on which a control circuit for controlling the driver circuit is formed. The power semiconductor devices are mechanically coupled to a heat sink for dissipating heat from the semiconductor devices. In order to downsize the power supply apparatus, the control printed circuit board may be mounted to the heat sink on which the power semiconductor devices are mounted, with the driver printed circuit board mounted between the power semiconductor devices and the control printed circuit board, to thereby assemble them into a single block. If, however, rigid boards are used for the control and driver printed circuit boards, dimensional errors and/or assemblage errors of such printed circuit boards may place strain on the power semiconductor devices, causing the semiconductor devices to float up from the heat sink, which impedes normal heat dissipation and may break down the power semiconductor devices. In addition, the printed circuit boards themselves may be also strained. When such power supply apparatus is transported or removed to another place, vibrations caused by the moving may be applied to the power supply apparatus. Then, the vibrations are superposed on the strain on the power semiconductor devices and the printed circuit boards, which may lead to breakdown of the printed circuit boards and the power semiconductor devices.
JP 7-7167 U discloses use of a flexible board for connecting components mounted on a case to components mounted on a printed circuit board attached to the case.
Similar flexible boards would be used to connect the above-described power semiconductor devices to the driver printed circuit board and to connect the driver printed circuit board to the control printed circuit board. This arrangement, however, would require two flexible boards in addition to the driver and control printed circuit boards. In addition, a space for disposing the flexible boards must be secured, which impedes downsizing of the power supply apparatus.
An object of the present invention is to provide an electrical apparatus, in which electrical components are prevented from being broken down and, still, which can be small in size.